US1573056A - Process of preparing 1, 8-aminonaphthol sulphonic acids - Google Patents

Description

Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

IVAN GUBELMANN AND JOHN M. 'I'INKIilR, OF SOUTH MILWAUKEE, WISCONSIN, AS- SIGNORS TO THE NEWPORT COMPANY, OF CARROLLVILLE, WISCONSIN, A COB- PORATION OF DELAWARE.

.PROCESS OF PREPARING LS-AMINONAPHTHOL SULPHONIC ACIDS.

No Drawing.

To all whom it may concern:

Be it known that we, IVAN GUBELMANN and JOHN M. TINKER, both citizens of the United States, and both residing at South Milwaukee, county of Milwaukee, Wiscon sin, have jointly invented certain new and useful Improvements in a Process of Preparing 1,8-Aminonaphthol Sulphonic Acids; and we do. hereby declare that the following is a full, clear, and exact description of the same.

This invention relates to the preparation of 1,8-aminonaphthol sulphonic acids by the fusion with caustic alkalies of l-naphthylamine sulphonic acids which contain a sulphonic acid group in the 8-position.

The ordinary fusion with caustic alkalies of 1-naphthylamine sulphonic acids con taining a sulphonic acid group in the 8- position constitutes a well-known method by which 1,8-aminonaphthol sulphonic acids are generally prepared on a technical scale. We have found that by following methods in use heretofore considerable decomposition takes place, through the splitting off of ammonia, resulting in the formation as an impurity of 1,8-dihydroxynaphthalene sulphonic acid. This decomposition not only lowers the yield but also causes the presence ofundesirable impurities in the finished product.

The present invention, therefore, has foran object the production of 1,8-aminonaphthol sill-phonic acids by an improved'method in which the fusion of l-naphthiylamine sulphonic acids which contain a sulphonic acid group in the 8-position is carried out with the least possible decomposition, resulting in excellent yields and a high quality of finished product.

Other and further important objects of this invention will be apparent from the disclosures in the following description, which sets forth the preferred form of our invention.

\Ve have found that the fusion with caustic alkalies of the l-naphthylamine sulphonic acids proceeds very much more smoothly in the presence of ammonia. The presence of ammonia introduced prior to the caustic allgali fusion prevents almost entirely the spl ing off of mm ma f rmed Application filed May 9, 1925.

thylamine-4,8-disulphonic Serial No. 29,215.

by the decomposition of the amino groups 1n the 1,8-naphthy lamine sulphonic acids used. 'VVe prefer to operate with ammonia pressures of from 150 1bs., but higher clave 400 lbs. water, 500 lbs. caustic soda and 500 lbs. caustic potash. Heat until dssolved and then charge 1000 lbs. of l-naphacid, as the mono-sodium salt. The autoclave is closed and ammonia gas is pressed into the autoclave up to a pressure of 100-150 lbs. The autoclave, is then heated to 190200 C., where it is held for a period of from 34 hours. After releasing the ammonia pressure on the autoclave, the finished fusion is worked up by the well-known method of d'ssolving in water and acidifying to precipitate the product. The resulting 1,8- aminonaphthol-4 sulphonic acid, commercially known as S-acid, is of very high qual ity and the yields obtained are excellent. The chemicalformula for S-acid is- OH NH:

SOaH

Ewample 2.-Charge into a steel autoclave with 400 lbs. water, 1000 lbs. caustic potash and 1000 lbs. 1-amino-2,4,8-naphthalene trisulphonic acid in the form of its tri-soda salt (either as the free amino or as the sultam compound). The autoclave is closed and ammonia is pressed into it up to a pressure of 100-150 lbs. The temperature of the mass is raised to 160-165 G. and maintained at that temperature during 3 1 hours. After releasing the pressure, the fusion is worked up by dilution and acidification in the usual way. After filtering and drying the precipitate, very ure 1,8- aminonaphthol-2,4-disulphonic aci is obtamed in the form of the mono sodium salt;

this product is commercially known as SS- acid, or 2S-acid. The chemical formula for 2S-acid is Soak 7 Example 3. Charge an autoclave with 1000 lbs. Water, 1000 lbs. caustic soda and 1000 lbs. 1-napl1thylamine-3,6,8-trisulphonic acid in the form of the di-sodium salt. After complete solution of the charged material, the autoclave is closed and 200 lbs. of 29% aqueous ammonia is added. The temperature of the mixture is gradually raised to l731 76 C. and main- SOaH SOIH If the various 1,8;aminonaphthol sulphonic acids made 'by' the foregoing examples are analyzed, it will be found that the amount of 1,8-dihydroxynaphthalene sulphonic acid present as impurity is practically nil, which fact clearly demonstrates the value of the ammonia pressure used in our fusion method. The resence of ammonia prevents the splitting ofi of the amino-group in the l-nap'hthylamine sulphonic acids, thereby causing higher yields and a distinctly improved quality of the finished product to be obtained.

We are aware that-numerous details of the process may be varied through. a wide range without departing from the spirit of naphthol-4 sulphonic acid, which includes the fusion with caustic alkalies of l-naphthylamine 4,8-disulphonic acid in the presence of ammonia.

3. The method of preparing 1,8-aminonaphthol-2,4-disulphonic acid, which in cludes the fusion with caustic alkalies of l-naphthylaminc-2,4,8-trisulphonic acid in the presence of ammonia.

4.'The method of reparin 1,8-aminonaphthol sulphonic acids, whic consists in fusing l-naphthylamine sulphonic acids containing a sulphonic acid group in the 8- position with caustic alkahes under ammonia pressure.

In testimony whereof we have hereunto subscribed our names/ IVAN GUBELMANN. JOHN M. TINKER.